Edible dispersions with a plastic rheology usually have a high fat content. Often the fat is present as a continuous fat phase. Well-known edible, plastic dispersions are, for example, butter and margarine.
Many attempts have been made to find a replacement for fat in edible products. One reason why such a fat replacer is desirable is the wish to reduce the caloric content of the food product and other dietetic considerations while at the same time lower production cost, in particular by reducing raw material cost. If both goals are achieved a resulting product must still have consumer acceptable flavor, mouthfeel and long shelf life.
One proposal as a fat substitute has been the use of a non-caloric gaseous or solid material such as air or silica. Other proposed fat replacers include substances that are physically similar to triglycerides but that cannot be digested by the human body, such as waxes, e.g., jojoba oil, and sucrose poly fatty acid esters. See, for example, JAOCS 63(3) (March 1986), 278-288. The results of these approaches have thus far been less than satisfactory. One of the problems with the indigestible physical analogues of triglyceride fat is that the material is only available in limited quantities, and the material cost is high. The gaseous and solid materials referred to above can be used to replace only a small part of the fat. At higher inclusion levels these fat extenders severely affect the properties of the resulting product.
A substance that has been widely applied as a fat extender is water. This use of water has, for example, led to the introduction of the so-called halvarines: a substitute for butter and margarine containing only about 40% instead of the usual 80-85% fat. However, as with air, for example, water can also be employed only to a limited extent before adverse effects on the product properties are observed. To overcome this disadvantage it has been suggested that water should be used in combination with thickening agents, and in particular with gelling agents. This approach has led to substantial improvements of such products with substantially reduced fat content like halvarine.
However, with these approaches it has been possible to replace only part of the fat of edible plastic dispersions. When only thickening agents are employed in combination with the water, a still essentially liquid system that does not retain its shape is obtained. The use of gelling agents in such liquid systems was observed to produce aqueous gels having elastic or brittle properties rather than being plastic. Thus, the thickened gelled aqueous systems were used in edible plastic dispersions only as fat extender to replace part of the fat. To maintain the required plastic rheology of the product, the use of a not negligible amount of fat, usually constituting the continuous phase of the edible plastic dispersion, was still necessary.
Although it has been stated in the art that certain gelled aqueous system have plasticity and spreading characteristics such that they can be used by themselves as spreads, e.g., for bread, to replace butter or margarine, in practice these systems were not found to be satisfactory. The gels were too elastic or brittle to be acceptable as a replacement for a plastic product. Moreover, the organoleptic properties of the products usually were poor.
Plastic Dispersions having relatively good plastic rheology are described in Cain et al., U.S. Pat. No. 4,956,193 issued on Sept. 11, 1990. These edible plastic dispersions do not have a continuous fat phase and include at least two condensed phases, at least one of which is continuous. The compositions contain (a) one gelling agent selected from the group of gelatin, kappacarrageenan, iota-carrageenan, alginate, agar, gellan, pectin and mixtures thereof and, (b) a second gelling agent selected from the group of a gelling starch, denatured whey protein, denatured soy protein, microcrystalline cellulose and mixtures thereof and one gelling agent is different from the other gelling agent.
It has been observed that these plastic dispersions can be quite slow gelling and take up to several weeks to gel set to a consistency which is useful for a resulting spread product. Some faster gel setting starches have been found to produce brittle or rubbery dispersions having off-flavors and poor mouthfeel. Further, some of such spreads have been seen to possess phase separation and lack stability on the shelf.